Physicists today announced that there is evidence of a new subatomic particle, which is seen by many as a potential key to explaining the universe.
The announcement brought cheers and a standing ovation for Peter Higgs (shown in image above), the Scottish physicist who predicted the existence of such a particle back in the 1960s. "I would like to add my congratulations to everybody involved in this tremendous achievement," he said. "For me, it's really an incredible thing that it's happened in my lifetime."
Results are preliminary; more studies to come over the next few years.
Those heading up the search for the Higgs boson, seen as the key to understanding why matter has mass, are unwilling to say for certain that is what they've seen. In a press release issued today, CERN, the European Organization for Nuclear Research, appeared to be cautiously optimistic and stressed that more research needed to be conducted:
At a seminar held at CERN today as a curtain raiser to the year's major particle physics conference, ICHEP2012 in Melbourne, the ATLAS and CMS experiments presented their latest preliminary results in the search for the long sought Higgs particle. Both experiments observe a new particle in the mass region around 125-126 GeV.
"We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV. The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage," said ATLAS experiment spokesperson Fabiola Gianotti, "but a little more time is needed to prepare these results for publication."
"The results are preliminary but the 5 sigma signal at around 125 GeV we're seeing is dramatic. This is indeed a new particle. We know it must be a boson and it's the heaviest boson ever found," said CMS experiment spokesperson Joe Incandela. "The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks."
"It's hard not to get excited by these results," said CERN Research Director Sergio Bertolucci. " We stated last year that in 2012 we would either find a new Higgs-like particle or exclude the existence of the Standard Model Higgs. With all the necessary caution, it looks to me that we are at a branching point: the observation of this new particle indicates the path for the future towards a more detailed understanding of what we're seeing in the data."
The results presented today are labelled preliminary. They are based on data collected in 2011 and 2012, with the 2012 data still under analysis. Publication of the analyses shown today is expected around the end of July. A more complete picture of today's observations will emerge later this year after the LHC provides the experiments with more data.
The next step will be to determine the precise nature of the particle and its significance for our understanding of the universe. Are its properties as expected for the long-sought Higgs boson, the final missing ingredient in the Standard Model of particle physics? Or is it something more exotic? The Standard Model describes the fundamental particles from which we, and every visible thing in the universe, are made, and the forces acting between them. All the matter that we can see, however, appears to be no more than about 4% of the total. A more exotic version of the Higgs particle could be a bridge to understanding the 96% of the universe that remains obscure.
"We have reached a milestone in our understanding of nature," said CERN Director General Rolf Heuer. "The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle's properties, and is likely to shed light on other mysteries of our universe."
Positive identification of the new particle's characteristics will take considerable time and data. But whatever form the Higgs particle takes, our knowledge of the fundamental structure of matter is about to take a major step forward.
Rolf Heuer, CERN General Director, told those at the conference, "As a layman, I would say we have it. But as a scientist, I have to say, what do we have?"
The 'God Particle' and the Big Bang.
Two independent teams at the large Hadron Collider who were studying high energy collisions of protons say that they have observed the particle, which is behaving a bit differently than predicted, generating excitement from those who study dark matter, anti-matter and the Big Bang.
The Big Bang is the massive explosion that many theorize created the universe. Studies will be conducted over the next months and years, revealing more about the first microseconds of the universe's creation.
The use of the term "God particle" has been by the media, and generally disliked by scientists. According to Wikipedia, the title came from Leon Lederman's popular science book on particle physics, The God Particle: If the Universe Is the Answer, What Is the Question? The term "God particle" is said to overstate the particle's importance, not least since its discovery would still leave unanswered questions about the unification of quantum chromodynamics, the electroweak interaction, and gravity, as well as the ultimate origin of the universe. Higgs is an atheist, and is displeased that the Higgs particle is nicknamed the "God particle", because the term "might offend people who are religious."
Higgs boson explained for laypeople.
John Ellis, theoretical physicist, explained what the Higgs boson is and why more research is required (see video embedded below):
Since 1964, we have had this idea proposed by [FranÃ§ois] Englert, [Robert] Brout and Higgs that empty space is like a medium. As particles travel through this medium, some of them interact with it, some of them don't interact with it. The ones that do interact with this medium acquire masses, and the ones that pass through without interacting, those are mass-less particles. So Higgs boson has this job of giving masses to all the other elementary particles.
Let me give you an analogy. Imagine an infinite field of snow extending throughout all of space, flat, featureless, going in all directions ... maybe the middle of Siberia. Now imagine that you are trying to cross this field of snow. So maybe you are a skier, and you skim across the top. That's like a particle that does not interact with the Higgs field. It doesn't sink into the snow. It goes very fast. It's like a particle with no mass, traveling at the speed of light. But maybe you've only got snowshoes. In that case, you sink into the Higgs "snowfield." You've got less speed than the skier, less than the speed of light. That's like a particle with mass because you are connecting, interacting with that Higgs snowfield. And then finally, if you've just got boots on, then you sink deeply into the snow. You go very, very slowly, and that's like a particle with a big mass.
So think of this Higgs field as being like this universal field of snow. Now, where does the Higgs boson come in?
We all know what snow is made out of, right? It's made out of snowflakes. In the same way, this universal Higgs snowfield is made up of little quanta. Those quanta are like snowflakes. That's what we call the Higgs boson.
If you look at the basic equations of the standard model, as written on my t-shirt, they are very symmetric. The way in which the different particles appear is the same. At least on the top two lines, there's nothing to distinguish particles which have different masses, for example. But this symmetry has to be broken. Electrons are lighter than neutrons; the top quark is much heavier than the quarks that make up everyday nuclei. So the top two lines, the symmetric lines, cannot be all there is. There has to be something to discriminate, distinguish between the two different types of particles. That's the job of the Higgs boson. That's the job of the two bottom lines. Depending on how those different types of quark, or electron and the neutron, depending on how they connect to that Higgs field, that Higgs boson, we believe they get different masses. The symmetry between these particles is broken.
The amount of data that ATLAS and CMS have each obtained should be enough to, I think, convince most people that there's something there. To say you've discovered the Higgs, it's a complicated story.
It's one thing to see evidence of a new particle, but you have to check whether it has the right properties. And to check whether it has the right properties will actually take quite a bit of extra work. Carl Sagan once said that extraordinary claims require extraordinary levels of proof. Before we can say that we have discovered the Higgs boson, we have to be absolutely, absolutely sure, and that will probably take a bit more time. But I expect that by the end of the year, we will be absolutely certain one way or the other.